Re: Explicit destructor call - problem with typedef from other
namespace
PiotrN wrote:
Imagine simple code:
namespace a {
class A { public: virtual ~A() { cout << "~A()"; }};
typedef A TA;
class B : public A { public: virtual ~B() { cout << "~B()"; }};
}
and 3 different usages:
[...]
2) This doesn't compile "20:error: expected class-name before ?(?
token".
int main() {
char buf[100];
a::TA *p = new (buf) a::B;
p->~TA(); //line 20
}
I'd expect this, though you could argue differently. The point is that
using the "a::A*" as a base, there is no "TA" that can be found. To
some extent, anything beginning with the tilde can only be a
destructor, but the name is still required, and TA is neither a fully
qualified name nor can it be resolved. Note that the reason this
behaviour could be argued is that ADL would also find an according
function in the namespace enclosing the parameters.
3) This compiles but produces unexpected output: ~A().
I understand this because it is not "virtual" call of destructor.
int main() {
char buf[100];
a::TA *p = new (buf) a::B;
p->a::TA::~TA();
}
Right, here you are explicitly calling just one specific destructor,
overriding the dynamic dispatch.
How about "p->~a::TA()", have you tried that?
If "using namespace a" added to case #2 - everything works fine.
Adding "using a::TA" should also do the trick without pulling in
everything from namespace "a".
Good luck!
Uli
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